Postinfectious fatigue: prospective cohort study in primary care

The idea that chronic fatigue has an infectious origin has become
popular, but the main evidence for such an association has
come from retrospective case-control studies, which are
subject to ascertainment bias. We report a prospective study
of the outcome of clinically diagnosed infections in patients
presenting to UK general practitioners. Questionnaires
assessing fatigue and psychiatric morbidity were sent to all
patients aged 18-45 years in the study practices. The
prevalence of chronic fatigue and chronic fatigue syndrome was
then ascertained among 1199 people aged 18-45 who presented to
the general practitioners with symptomatic infections and in
1167 people who attended the surgeries for other reasons. 84%
were followed up at 6 months. 9.9% of cases and 11.7% of
controls reported chronic fatigue (odds ratio 1.0 [95% CI
0.6-1.1]).

There were no differences in the proportions who
met various criteria for chronic fatigue syndrome. No effect
of infection was noted when we excluded subjects who reported
fatigue or psychological morbidity at the baseline screening.
The strongest independent predictors of postinfectious fatigue
were fatigue assessed before presentation with clinical
infection (3.0 [1.9-4.7]) and psychological distress before
presentation (1.8 [1.2-2.9]) and at presentation with the
acute infection (1.8 [1.1-2.8]). There was no effect of sex or
social class. Our study shows no evidence that common
infective episodes in primary care are related to the onset of
chronic fatigue or chronic fatigue syndrome.